[R-sig-teaching] Shading the solution of quadratic inequality
rpruim at calvin.edu
Thu Feb 16 16:11:12 CET 2012
The xlim=c(-6,-2) is extraneous in the code below. It snuck in from
something else I was doing. It doesn't hurt any, but it doesn't do
anything either since the plotting limits are inferred from the
surrounding plot when add=TRUE is used.
On Feb 16, 2012, at 10:07 AM, Randall Pruim wrote:
> I'm not sure exactly what sort of plot was desired, but I'll offer
> 1.5 possibilities.
> Currently you can do something like this:
> plotFun( x^2 - 4 ~ x , xlim=c(-6,6), col='blue' )
> plotFun( (x^2 - 4)/as.numeric(x^2 -4 > 0) ~ x , xlim=c(-6,-2),
> add=TRUE, col='blue', lwd=4 )
> It is a bit of kludge since I'm using division by 0 to hide part of
> the function. You can adjust colors, line thickness, and alpha to
> your particular sensitivities. And you can use type='h' if you want
> a "filled in version".
> Soon, you should be able to do
> plofFun( x^2 - 4 ~ x, groups=(x^2-4>0) )
> If you find yourself wanting to plot "mathematical" functions like
> this, I encourage you to give plotFun() a try and let us know how
> you like it.
> On Feb 16, 2012, at 9:42 AM, R. Michael Weylandt wrote:
>> You should probably say more about which graphics engine you are
>> using, but here's a start:
>> curve(x^2-4, from = -3, to = 3)
>> x <- seq(-3, 3, length.out = 200)
>> polygon(c(x, rev(x)), c(x^2-4, rep(Inf, length(x))), col = 2)
>> The red is a little "oppressive" so I'd try to add transparency if
>> your device supports it. Adding a shade above/below argument to curve
>> based on the same principles might be a fun exercise too...
>> On Thu, Feb 16, 2012 at 9:13 AM, AbouEl-Makarim Aboueissa
>> <aaboueissa at usm.maine.edu> wrote:
>>> Dear all R Users:
>>> How can I shade the solution (-Inf,-2) or (2,Inf) of the
>>> inequality -x^2+4<0 within the curve of f(x)=-x^2+4.
>>> the solution (-Inf,-2)or(2,Inf) of the inequality x^2-4>0 within
>>> the curve of
>>> with many thanks
>>> AbouEl-Makarim Aboueissa, Ph.D.
>>> Associate Professor of Statistics
>>> Graduate Program Coordinator
>>> Department of Mathematics & Statistics
>>> University of Southern Maine
>>> 96 Falmouth Street
>>> P.O. Box 9300
>>> Portland, ME 04104-9300
>>> Tel: (207) 228-8389
>>> Fax: (207) 780-5607
>>> Email: aaboueissa at usm.maine.edu
>>> aboueiss at yahoo.com
>>> Office: 301C Payson Smith
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